This research demonstration application from a group of university-based substance abuse research scientists collaborating with a group of municipal government agencies has the objective of developing and evaluating an innovative mobile health service unit approach to enhancing drug abuse treatment. With a focus upon the identification and recruitment of I.V. drug abusers, the model mobile service will expand the availability of drug abuse treatment, health education, outreach, and clinical support to targeted inner city communities with a high prevalence of substance abuse and other poor health status indicators. The project will-involve two mobile units, each consisting of a large specially equipped travel trailer towed by a converted van. One unit will visit 4 to 5 locations in the City of Baltimore each day for 12 to 18 months to increase service accessibility. The second unit will remain stationary for the initial 12-18 months of the project in a demographically comparable area of Baltimore but will deliver comparable services and be comparably staffed. In addition to general health care services, the two units will be capable of delivering full outpatient treatment services to 150-200 drug abusers, including urine and AIDS testing, medications, and drug abuse counseling. Evaluation of the project will focus upon a comparison with traditional health services in terms of drug abuse treatment accessibility and effectiveness. Specific research questions regarding the enhancement of recruitment and drug abuse treatment retention will be addressed using a crossover design with the initially stationary health service unit becoming mobile for an additional 12-18 months in its demographically circumscribed area while the originally mobile health service unit becomes stationary in its demographically comparable area of the City of Baltimore.